With the Raman microscope, for example, it is important to block light from the surrounding, namely, ambient light in order to detect weak Raman scattered light. It is also important that laser light which illuminates a sample be sufficiently prevented from leaking to the surroundings. As disclosed in Patent Documents 1 to 3 to be mentioned below, it has been common practice to dispose a cover member made of a thin metal plate which covers at least principal parts of the microscope, and to configure at least a part of the cover member to be openable and closable.